What is microcephaly?

Microcephaly is a neurological disorder in which the circumference of the head (the measured distance around the top) is smaller than average for an infant’s size and age. The disorder can be present at birth or acquired during the first few years of a child’s life. Microcephaly is often associated with some degree of mental retardation. However, in 15 percent of the cases, the child has normal intelligence. Microcephaly is rare, occurring from 1 per 6200 to 8500 births.

What causes microcephaly?

The growth of the skull is determined by the expansion of the brain. Microcephaly occurs most often because the brain fails to grow at a normal rate. This can be caused by a variety of conditions or exposure to harmful substances during fetal development. Some of these causes include:

  • Chromosomal disorders such as Down’s syndrome, Cri du chat syndrome, Trisomy 13, and Trisomy 18
  • Maternal viral infections such as rubella (German measles), toxoplasmosis, and cytomegalovirus
  • Maternal alcoholism or drug abuse
  • Maternal diabetes
  • Mercury poisoning
  • Uncontrolled maternal PKU
  • Maternal malnutrition

Acquired microcephaly might occur after birth due to various brain injuries such as lack of oxygen or infection.

What are the symptoms of microcephaly?

Aside from a noticeably smaller head, the following are the most common symptoms of microcephaly.

  • High-pitched cry
  • Poor feeding
  • Convulsions
  • Increased movement of the arms and legs (spasticity)
  • Hyperactivity
  • Developmental delays
  • Mental retardation

As the child grows older, his or her face continues to grow while the skull does not. This causes the child to develop a disproportionately large face, a receding forehead and a loose, often wrinkled scalp. The rest of the body is often underweight and proportionately smaller than normal.

How is microcephaly diagnosed?

Microcephaly can sometimes be diagnosed before birth by prenatal ultrasound. In many cases, however, it might not be evident by ultrasound until the third trimester, and therefore might not be seen on ultrasound performed earlier in pregnancy.

Most of the time, the diagnosis will not be made until birth or later in infancy. Along with noting that the baby's head circumference is much smaller than normal, the doctor will perform a complete physical examination and obtain a complete prenatal and birth history of the child. In the case of later development of the disorder, the doctor might ask the parents about developmental milestones such as crawling and walking, since microcephaly is frequently accompanied by mental retardation.

How is microcephaly treated?

Generally there is no specific treatment for microcephaly. Since microcephaly is a life-long condition that is not correctable, management of the condition includes maximizing the child's capabilities at home and in the community. Positive reinforcement will encourage the child to strengthen his or her self-esteem and promote as much independence as possible.

The full extent of microcephaly is usually not completely understood immediately after birth, but might be revealed as the child grows and develops.

A child born with microcephaly requires frequent examinations and diagnostic testing by a doctor to monitor the development of the head as he or she grows. The medical team works with the child's family to provide education and guidance to improve the health and well-being of the child.

What is the prognosis for microcephaly?

Prognosis for microcephaly varies, and depends on the presence of other existing medical conditions. In general, however, life expectancy for children with microcephaly is reduced, and the prospects of attaining normal brain function is poor.


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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/4/2011...#9843